The Theory and Performance of NovAtel Inc.'s Vision Correlator

This paper provides an overview of the general principles and early performance results of the Vision Correlator. The Vision Correlator is a new method of measuring and processing the synchronization signals of a received PRN code. It is a significantly different process than any of the various correlation methods used in GNSS receivers today. It works by precisely measuring the received Radio Frequency (RF) characteristics in the time domain of the phase transitions of the modulated signal broadcast from the satellite. It is particularly useful in detecting and removing close-in multipath. Simulation results show that the Vision Correlator can remove the effects of a multipath signal on the code and carrier measurements when the delay of the multipath signal is less than 10m from the line of sight signal, and mitigate their effect to a fraction of a meter (code). It also provides a very useful statistic that can be used for Signal Quality Monitoring of the received signal. This statistic can be used to filter data that is unrepairable.